Answer: The COM interface class from which all other interface classes are derived. This interface allows all COM objects to manage their own lifetime, ie, to release themselves from memory when they are no longer connected to any clients.

The COM interface class from which all other interface classes are derived. This interface allows all COM objects to manage their own lifetime, ie, to release themselves from memory when they are no longer connected to any clients. Source: CoolInterview.com

IUnknown Interface is the Interface which every COM should have. The Three parts are:1. QueryInterface2. Addref3. release